The invention relates to a filler neck for a fuel tank of a motor vehicle. More particularly, the invention relates to a filler neck with a shutter which is mounted inside the filler neck and can be brought by a pump nozzle into an open position for filling the fuel tank and into a closed position via an actuating mechanism for closing the filler neck.
A filler neck for a fuel tank of a motor vehicle is known, for example, from WO 99/03697. In this filler neck, an internally mounted shutter is provided, which replaces the generally conventional tank caps capable of being either screwed on or attached via a bayonet fastening from outside to the filler neck of the fuel tank. The shutter, when in a closed position, ensures a gas-tight and liquid-tight seal between the fuel tank on one side and the ambient air on the other side. An actuating mechanism operates in such a way that the shutter is immediately closed as soon as a fuel pump nozzle has been drawn out of the filler neck. With the shutter in the closed position, any fuel droplets still running out of the fuel pump nozzle can no longer run off into the fuel tank. These fuel droplets remain on the closed shutter or in the region outside the latter and evaporate into the ambient air in an undesirable way.
The disadvantages of the prior art may be overcome by providing a filler neck for the fuel tank of a motor vehicle comprising a housing having a tubular port defining an orifice in fluid communication with the fuel tank of the vehicle. A shutter is coupled to the housing and operable between a closed position closing the orifice of the tubular port and an open position opening the orifice to allow fluid into the fuel tank. An actuating mechanism is operatively coupled between the housing and the shutter for actuating and biasing the shutter from the open position to the closed position. The actuating mechanism includes a lever pivotally coupled to the housing and cooperative with the shutter for automatically moving the shutter from the open position to the closed position. A damping device is operatively coupled to the lever for delaying the automatic movement of the shutter from the open position to the closed position upon removal of a fuel pump nozzle from the tubular port thereby allow any residual fuel from the nozzle to enter the orifice prior to the shutter reaching the closed position.
The object on which the invention is based is, therefore, in a filler neck of the type initially mentioned, to ensure in a simple way that the fuel droplets still subsequently running out no longer evaporate into the ambient air.
The set object is achieved, according to the invention, in that the actuating mechanism of the shutter cooperates with a damping device during the closing movement, in such a way that the shutter can be closed with a time delay.
This ensures in a simple way that droplets subsequently running out have sufficient time to run off in the direction of the fuel tank.
It is also particularly advantageous if the damping device is uncoupled from the actuatin mechanism when the shutter is closed. This ensures that any functioning of the spring-loaded shutter as a vacuum valve cannot be impaired and cannot be influenced by the damping device.
An embodiment of the invention is preferred, in which the shutter can be brought into its open position in a manner at least essentially uninfluenced by the damping device. The opening of the shutter during the introduction of the pump nozzle therefore does not require any additional forces to be overcome. This therefore also ensures that the damping device does not have to be co-actuated during the opening of the shutter, this being advantageous, for example, in the case of relatively low outside temperatures, where extra loads on the actuating mechanism could result in damage to the latter.
If, then, the actuating mechanism of the shutter is designed in such a way that it has an actuating lever which acts upon the shutter and cooperates with a first row of teeth on a toothed rack, there can be provision in a simple way, to ensure cooperation with a damping device, for the rack to have a second row of teeth which, during the opening movement of the shutter, can be brought into engagement with a gearwheel or the like which is operatively connected to the damping device.
In this embodiment, the desired uncoupling of the damping device from the actuating mechanism of the shutter when the latter is in the closed position can follow in a very simple way, in that, during the closing movement of the shutter, the gearwheel comes out of engagement again with the rows of teeth on the rack.
In this embodiment, it is also particularly advantageous if the damping device is a rotary damper which can be actuated in its undamped direction of rotation during the opening movement of the shutter. A rotary damper is particularly suitable for cooperating with the already existing rack and takes up only a small amount of space.
In the present invention, however, other types of damping devices, such as, for example, a linear damper, may advantageously also be used. Depending on the type of damping action or damping mechanism, silicone-oil dampers, air dampers or friction dampers, or the like, may be considered.